2013 BHCSI Object-Oriented Design in Python
Test #2 (100 points) Solutions
7/24/2013
1) (15 pts) Complete the program below so that it reads in a sentence entered on a line by
itself by the user and reports the number of words in the sentence and the length of the
longest word in the sentence.
def main():
sentence = input(“Please enter your sentence.\n”)
tokens = sentence.split()
numWords = len(tokens)
# 3 pts
# 3 pts
numChars = len(tokens[0])
for i in range(len(tokens)):
if len(tokens[i]) > numChars:
numChars = len(tokens[i])
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print(“Your sentence has”, numWords, “words.”)
print(“The longest word has”, numChars,”characters.”)
main()
2) (10 pts) The Lucas numbers are defined as follows: L1 = 1, L2 = 3, Ln = Ln-1 + Ln-2 for
all n > 2. (Thus, the next few Lucas numbers are 4, 7, 11 and 18.) Write a recursive
function that takes in n and returns the nth Lucas number. You may assume n is a positive
integer.
def lucas(n):
if n == 1:
return 1
elif n == 2:
return 3
else:
return lucas(n-1) + lucas(n-2)
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# 5 pts
3) (12 pts) Complete the following function that takes in a list of numbers and returns the
product of all of the numbers in the list.
#Takes a list of numbers and returns the product
def multiply(numbers):
product = 1
for i in range(len(numbers)):
product = product*numbers[i]
# 2 pts
# 4 pts
# 4 pts
return product
# 2 pt
4) (12 pts) What is the output produced by the following code segment:
def func(n):
if n < 5:
print(n, end=” “)
else :
print(n%5, end=” “)
func(n//5)
func(67)
print()
func(116)
2 3 2
1 3 4 (2 pts each number)
5) (10 pts) What will the following code segment print (Don’t worry about ordering for the last
line)?
x = {'Pie':'Dog', 'Bro': 'Bacon', 'John':'Asia', 'Eggs':'Ralph'}
if 'Ralph' in x:
print("Hello Ralph!")
if 'John' in x:
print("John is here!")
print(x['Pie'])
for i in x:
print(i, end = ' ')
John is here! # 2 pts, 2 pts for not having Ralph
Dog
# 2 pts
Bro Eggs John Pie # 1 pt each
6) (13 pts) Complete the recursive function below that it prints all odometer readings of
length n that have digits in strictly increasing order with the prefix current.
def printIncOdometer(n, current):
if len(current) == n:
print(current)
return
start = 0
if len(current) > 0 : # 1 pt
start = int(current[len(current)-1])+1 #6 pts
for i in range( start ,10):
# 2 pts
printOdometer( n , current+str(i) )
#1pt 3 pts
7) (25 pts) Write a function that takes in two dictionaries that map items to prices and
returns a new “merged” dictionary that contains each item in either dictionary. If an item
is contained in exactly one of the dictionaries, keep its price as stated. If an item is
contained in both dictionaries, in the merged dictionary set its price to the minimum of
the two prices. Remember, you should NOT make any changes to either of the two
existing dictionaries. Instead, you’ll create a third new dictionary and add to it all unique
items from the two input dictionaries, setting the prices as previously mentioned.
def makeMergedPriceList(priceListA, priceListB):
ans = {}
# 2 pts
for item in priceListA.keys():
ans[item] = priceListA[item]
# 4 pts
# 4 pts
for item in priceListB.keys():
# 4 pts
if (not item in ans.keys()) or priceListB[item] < ans[item]:#6p
ans[item] = priceListB[item] # 4 pts
return ans
# 1 pt
8) (3 pts) What items are primarily sold at Books-A-Million?
Books (3 pts)